Showing papers by "Wayne V. Sorin published in 2001"

System and method for optical heterodyne detection of an optical signal including optical preselection that is adjusted to accurately track a local oscillator signal

Abstract: An optical heterodyne detection system includes a tunable optical pre-selector that is adjusted to track the frequency of a swept local oscillator signal. The tunable optical pre-selector is adjusted in response to a measure of the frequency of the swept local oscillator signal and in response to a measure of a portion of the swept local oscillator signal after the portion of the swept local oscillator signal has optically interacted with the optical pre-selector. In an embodiment, at least some portion of the swept local oscillator signal is modulated before it interacts with the optical pre-selector. In an embodiment, the portion of the swept local oscillator signal that interacts with the pre-selector is detected and used in a feedback control circuit to generate a control signal which causes the error between the center frequency of the pre-selector and the frequency of the swept local oscillator signal to be small.

Characterization of human scalp hairs by optical low-coherence reflectometry

Abstract: Optical low-coherence reflectometry is used to investigate the internal structure and optical properties of human scalp hair. Regardless of hair color, the refractive index of the cortical region remains within the range of 1.56-1.59. The amplitude of the backscattered infrared light coupled into different-colored hair confirms the relative melanin content. Discontinuities in the refractive index permit identification of distinct structural layers within the hair shaft.

Dynamically tunable optical amplifier and fiber optic light source

Abstract: An optical amplifier comprises a wavelength tunable filter, one or more optical gain stages, and a controller for controlling a spectral profile of the wavelength tunable filter in response to a measured spectral characteristic of the amplifier. The controller may also control gain of the gain stage(s). The controller determines the filter spectral profile necessary to obtain a desired amplifier spectral characteristic. The spectral characteristic may, for example, be a power spectral output of the amplifier or a gain profile of the amplifier. The amplifier may incorporate a dispersion compensator. The controller may control a spectral profile of the wavelength tunable filter and gain of the dispersion compensator. A tunable fiber light source is also described.

Channel equalizer with acousto-optic variable attenuators

Abstract: An optical communication assembly has an optical cross connect coupled to a first, a second, a third and a fourth set of optical fibers. A first demultiplexer (160) is coupled to a first input fiber and the first set of optical fibers and a second demultiplexer (168) is coupled to a second input fiber and the second set of optical fibers. A first multiplexer (162) is coupled to a first output fiber and the third set of optical fibers. A second multiplexer (170) is coupled to a second output fiber and the fourth set of optical fibers. A first set of attenuators (152) is coupled to the third set of optical fibers and a second set of attenuators(152) coupled to the fourth set of optical fibers. The attenuators may consist of acousto-optic tunable filters and are controlled by an electronic feedback loop.

Autoalignment and autofocus mechanism for coupling light between an optical fiber and a physical specimen

Abstract: An apparatus for applying an optical signal to a surface and collecting the light leaving the surface in response to the application of the optical signal. The optical signal and the collected light traverse an optical fiber having an end proximate to the surface which delivers light to the surface with the aid of a lens that couples the optical signal to the surface, collects the light emitted by the surface, and couples collected light into the optical fiber. A detector measures the intensity of light delivered into the optical fiber and generates a detection signal indicative of the measured intensity as a function of time. A set of actuators dither the position of the lens relative to the proximate end of the fiber. Each actuator operates at a different dither frequency and moves the lens relative to fiber along a different axis. The average position of the lens relative to the proximate end of the fiber along each axis is adjusted so as to maximize the average power detected at the corresponding dither frequency.

Tunable filter with core mode blocker

Abstract: An optic apparatus includes an optical fiber with a cladding surrounding a core and a core-mode blocker included in at least a portion of an interactive region of the optical fiber. A mode coupler is coupled to the optical fiber and couples a first mode to a different spatial mode in a forward direction of the optical fiber.

Add/drop acousto-optic filter

Abstract: A drop AOTF has a first AOTF that includes an optical fiber with a longitudinal axis, an acoustic wave propagation member with a proximal end and a distal end and an acoustic wave propagation member. The acoustic wave propagation member propagating an acoustic wave from the proximal to the distal end of the acoustic wave propagation member. An optical circulator, with first, second and third ports, is coupled to the first AOTF at the third port. A mode coupler is coupled to the first AOTF. An orthogonal-polarization reflective mirror is coupled to the mode coupler.

Optical apparatus with faraday rotator, static gain flattening filter and variable optical attenuator

Abstract: An optical apparatus for transmitting an optical signal includes a static filter, a Faraday rotator and a reflector. The Faraday rotator makes a first change in polarization of an optical signal in a first direction, and a second change in polarization of the optical signal received from the reflector in a second direction. This produces a polarization of the optical signal that is substantially orthogonal to an initial polarization state of the optical signal.

Tunable Fabry-Perot filters and lasers having increased tuning range and reduced frequency noise

Abstract: A tunable optical cavity[200, 300] constructed from a fixed mirror[214] and a movable mirror. The fixed mirror[214] is attached to a substrate[203] having a first electrically conducting surface. A support member[216] having the moveable mirror[213] supported thereon and having a second electrically conducting surface, is suspended above the substrate[203]. A circuit[250] applies an electrical potential between the first and second electrically conducting surfaces thereby adjusting the distance between the fixed and movable mirrors. The fixed mirror[214] and the moveable mirror[213] are positioned such that the mirrors form the opposite ends of the optical cavity[200]. The distance between the fixed mirror[214] and the moveable mirror[213] is a function of the applied electrical potential. The fixed mirror[214] is mounted in a well in the substrate[203] such that distance between the support member[216] and the substrate[203] is less than half the distance between the mirrors.

Tunable narrow band optical filter

Abstract: A method, an apparatus and a system are described for receiving an optical signal in an optical filter and routing the optical signal through the optical filter multiple times